Method for treating external human eye diseases due to a deficiency of tears are known which consist of using punctum plugs and implants to treat keratoconjonctivis sicca, referred to in common language as "dry eye", due to the insufficient production of tears or to an excessive drainage of the lacrimal liquid.
This disease is relatively frequent, particularly among the elderly. With age, the eye produces less tears (about 0.6 times less at the age of 65 than at the age of 18). The tears are generated permanently by small glands and temporarily by the large lacrimal gland flow over the eye and drain through small openings called puncta in the lids of the eyes corresponding with canaliculi which direct the tears towards the nose.
Some devices have already been proposed to be placed in the lacrimal system to diagnose and treat various conditions. One of these devices is known as punctum plug and is described by Jerry M. FREEMAN, MD., in US. Pat. No. 3,949,750. This plug is designed to completely close the punctum opening and comprises a slightly larger portion projecting in the vertical portion of the canaliculus that prevents the plug from extruding and a larger smooth head at the upper part that prevents the plug from passing down into the canaliculus.
The head is dome shaped to allow it to rest in the lacrimal pool and against the conjunctiva and cornea with little irritation. This plug, however, is prone to being pulled out by the plug wearer.
On the other hand, it is also known that a "PYREX" (registered Trademark) was designed by Dr. Lester JONES for placement in the canaliculus to maintain a pathway from the eye to the nose.
Another implant for treating external human eye conditions due to a deficiency of tears is disclosed in the European Patent No. 0,181,165 to HERRICK. A blockage is obtained in placing an implant within the horizontal portion of at least one of the canaliculi of the patient's eye.
Another known disease arises from the fact that one of the two canaliculi is stenosed and in this case the tears drain off on the patient's check in lieu of flowing through the tear ducts and out the nose. This condition becomes rapidly unbearable to the patient, the lacrimal production being permanent.
The current method to remedy this condition consists of passing a silicone tubing in the two canaliculi, upper and lower respectively, and tying the two ends of the silicone tubing in a knot inside the nose. In this case, however, the tubing appears in the palpebral opening (as a loop between the two punctae) and poses a risk of a hazardous extraction. Furthermore, only one intubation may be sufficient as it is rare that the two canaliculi are stenosed at the same time.